The Deep Western Boundary Current from Greenland to Argentina - One Century Long Observations Reveal Multidecadal Variability

The Deep Western Boundary Current (DWBC) is a major pathway for newly ventilated North Atlantic Deep Water (NADW) towards the South Atlantic and beyond. We revisit and analyse hydrographic measurements taken during the last 100 years along the coastline of the Americas in the DWBC. Long term fluctuations in salinity and temperature (spicyness) reveal an oscillation on the order of 30 years, with variations depending on depth. Anomalies can be traced along the coast with propagation speeds similar to those revealed in tracer analysis, though in the Northern Hemisphere for the complete time span of the last 60 years. The data south of the equator is to sparse to make a similar reliable conclusion for the South Atlantic. We discuss the stability and strength of this DWBC signal as well as its origin. The impact on changing the deep basin temperatures through this pathway is estimated.